This invention relates to a device for shaping the cross section of a light beam, including at least one beam shaping unit, with beam splitter means, beam deflection means and beam combining means, the beam splitter means being able to divide a light beam which is incident on the beam shaping unit into two component beams, the beam deflection means being able to deflect at least one of the component beams onto the beam combining means, and the beam combining means being able to combine the two component beams, such that the cross section of the light beam emerging from the beam shaping unit compared to the light beam entering the beam shaping unit is reduced in at least one direction.
Furthermore this invention relates to an arrangement for coupling a light beam which proceeds from an elongated laser light source with an elongated cross section into an optical fiber, comprising a laser light source, at least one collimation unit for collimating the light beam which emerges from the laser light source, and at least one focusing unit for focusing the light beams onto an optical fiber.
Furthermore the invention relates to a beam rotation unit for one such device, the beam rotation unit comprising at least one prism which can be located in the beam path of at least one light beam such that the cross section of the light beam passing through at least one prism can be turned by at least two reflections, especially rotation by 90° being able to take place.
A device of the aforementioned type and an arrangement of the aforementioned type are disclosed by German patent DE 195 37 265 C1. In the embodiment of a beam shaping unit which is described in it a rhomboid prism pair which separates the incident radiation into two component beam pencils is used as the beam splitter means. The beam deflection means is two half cubic prisms which are integrated into the corresponding component beam paths, as a result of the relatively long path of the component beam pencil which has been traversed in this beam shaping unit there being another lens located between the rhomboid prism pair and the half cubic prisms. The beam combining means is a fifth prism which deflects the component beam pencils, which are incident on it, and combines them again.
The disadvantage in such a beam shaping unit is that a total of seven components are used, each of the individual component beams passing through either optionally partially absorbing surfaces of optical components and each being reflected on two other surfaces of the aforementioned components which may not be 100% reflective. As a result of the many surfaces which must be transmitting or on which there must be reflection, a relatively high cost must be borne to improve these surfaces accordingly with regard to transmission and reflection. In particular, when several of these beam shaping units are set up in succession, such a beam shaping device will be less effective. Furthermore, as a result of the many components, which are used, and the high improvement cost these beam shaping units will be extremely expensive.
An arrangement of the initially mentioned type is generally used when for example the laser radiation emerging from a laser diode bar is to be focused on an optical fiber. In particular, as a result of the almost line-shaped laser light source with individual emission centers which are located spaced apart over the length of the line and the different divergences in the slow axis direction and fast axis direction, it is a good idea to use a beam shaping device of the initially mentioned type in order to repeatedly shape or fold together the laser light emerging from the laser diode bar with an almost line-shaped cross section so that a laser beam pencil with an almost square cross section is formed which can then be more easily focused on an optical fiber. The effectiveness and economic efficiency of this arrangement arises of course from the effectiveness and economic efficiency of the beam shaping unit used in it.
A beam rotation unit of the initially mentioned type is known from U.S. Pat. No. 5,513,201. By means of the beam rotation units described in it the laser radiation emerging from the laser diode bars will be focused on an optical fiber. In the already described divergences in the slow axis and the fast axis direction of the laser light emerging from the laser diode bars rotation of the individual light beams is a good idea because in this way the divergences in the slow axis direction and the fast axis direction can be interchanged. The beam rotation units described in the aforementioned US patent use prisms for beam rotation. These prisms are however extremely complex in structure and can only be produced with a very high fabrication cost.
The object of this invention is to devise a beam shaping device of the initially mentioned type, a beam rotation unit and an arrangement of the initially mentioned type with an effective and economical structure.